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PubMed1965

POLYOMA-LIKE VIRIONS IN HUMAN DEMYELINATING BRAIN DISEASE.

Specimens of brain tissue obtained at autopsy from three patients suffering from progressive multifocal leukoencephalopathy (PML) were examined by electron microscopy. In specimens from all three cases particles similar to those of the papova virus group were present, confirming previous observations. By the negative staining method it was possible to define the morphological characteristics of the particles more precisely and it was shown that they are structurally similar to virions of the polyoma-SV40-K type. The need is emphasized for obtaining fresh unfixed diseased tissue from persons suffering from PML in order that the biological properties of the particles can be investigated.

Autopsy↗

PubMed1996

[Diagnosis by imaging of the brain affected by AIDS].

Neurological complications are frequent in patients with the acquired immunodeficiency syndrome (AIDS). They are caused by neural structures being affected by the virus itself, and/or the development of opportunist infections and neoplasias secondary to the immunodepression. Cerebral toxoplasmosis and human immunodeficiency virus (HIV) encephalopathy are the commonest encephalopathic disorders seen in these patients. Primary cerebral lymphoma, progressive multifocal leukoencephalopathy (PML), tuberculosis, etc. are less common. Computerized tomography (CT) and magnetic resonance (MR) are the most suitable techniques for diagnosis and follow-up of cerebral involvement in patients with AIDS. Although MR is more sensitive for the detection of lesions, particularly those in the white matter, CT is still the most widely used technique since its more readily available. Also it needs less cooperation from the patient. Although on some occasions combination of both techniques may suggest the aetiology of the lesion, these techniques are non-specific.

AIDS Dementia Complex↗

PubMed1988

Acquired immunodeficiency syndrome. Magnetic resonance patterns of brain involvement with pathologic correlation.

Magnetic resonance brain scans of 30 patients with either acquired immunodeficiency syndrome (AIDS) or AIDS-related complex were reviewed. Twenty patients had focally abnormal neurological examination results at the time of scanning. Pathological diagnosis was available in nine. Four patterns of abnormality were observed on T2-weighted images. Multiple discrete high-signal foci (pattern A) were found in patients with toxoplasmosis and progressive multifocal leukoencephalopathy. Large, bilateral patchy to confluent high-signal areas within the white matter (pattern B) represented a white matter encephalitis secondary to cytomegalovirus or human immunodeficiency virus. Generalized enlargement of the cortical sulci and ventricles (pattern C) probably reflected atrophic changes from the chronic human immunodeficiency virus infection and prolonged debilitating illness. Solitary high-signal-intensity lesions (pattern D) suggested a nonviral opportunistic infection. Differential diagnosis of brain abnormalities in patients with AIDS can be assisted by recognition of these characteristic patterns.

Acquired Immunodeficiency Syndrome↗

PubMed1994

Myelin degrading activity in the CSF of HIV-1-infected patients with neurological diseases.

Degradation of purified myelin basic protein (MBP) was studied by SDS gel electrophoresis after addition of CSF samples obtained from HIV-1-infected patients. An increase in MBP degradation was detected in patients with neurological complications, such as AIDS dementia complex (ADC) or progressive multifocal leukoencephalopathy (PML), when compared with patients with no neurological symptoms (NA) or with other neurological opportunistic infections (OI). In the ADC and PML patients, in addition to CSF proteolytic activity, an increase in CSF-MBP levels and presence of white matter lesions were also observed by neuroimaging (MRI). In other opportunistic infections of the brain, MBP levels but not anti-MBP proteolytic activity increased. Results suggest the involvement of proteases in the virus-induced demyelination.

AIDS Dementia Complex↗

PubMed1973

Human papovavirus (JC): induction of brain tumors in hamsters.

Eighty-three percent of hamsters inoculated at birth with JC virus, a human papovavirus isolated from brain tissue of a case of progressive multifocal leukoencephalopathy, developed malignant gliomas within 6 months. Three brain tumors have been serially transplanted as subcutaneous tumors. JC virus was isolated from five of seven tumors tested. Cells from four tumors were cultivated in vitro. These cells contained an intranuclear antigen with the characteristics of a T antigen, and this antigen was antigenically related to SV40 T antigen. Although virus was not recovered from extracts of serially cultured tumor cells, JC virus was rescued when one tumor cell line was fused with permissive cells.

Animals↗

PubMed2006

Natalizumab.

Medical therapeutics has entered a new and exciting era with the development of biological agents that target specific sites. In the studies performed to date, natalizumab, a humanized monoclonal antibody to alpha4 integrin, when administered intravenously at monthly intervals, appeared to be highly beneficial with respect to decreasing both relapse rate and contrast-enhancing lesions in multiple sclerosis. Salutary actions on other disease parameters were also observed. However, treatment with natalizumab was complicated by the development of a rare demyelinating disease of the brain--progressive multifocal leukoencephalopathy (PML)--that developed in three patients in clinical trials of the drug. Currently, the estimated incidence for the development of PML with natalizumab treatment is 1:1,000 after approximately 18 months of therapy; however, as the development of PML is a stochastic event, it is quite possible that higher rates will be observed after longer treatment courses. Curiously, other opportunistic infections were not observed at higher rates in the treated groups when compared to controls, suggesting a specific association between natalizumab, and perhaps other alpha4 integrin blockers, and PML. Postmarketing surveillance studies should answer this and other questions related to the use of natalizumab.

Antibodies, Monoclonal↗

PubMed1997

Molecular detection of JC virus in embalmed, formalin-fixed, paraffin-embedded brain tissue.

Embalmed tissues are adequate for the detection of JC virus in lesions of progressive multifocal leukoencephalopathy (PML) by immunohistologic and molecular methods. JC virus was readily detected in embalmed brain tissue using immunohistochemistry (IHC), in situ hybridization (ISH), and the polymerase chain reaction (PCR). Two brains were removed from bodies that had been embalmed at least 24 h prior to autopsy. They were subsequently post fixed in 10% buffered formalin for 10-14 days before dissection and molecular studies were performed. Though these techniques are not novel, their use in embalmed tissues is. Routine embalming should not eliminate these diagnostic procedures from consideration.

Brain↗

PubMed2001

Human neurotropic JC virus and its association with brain tumors.

JC virus (JCV) is a human polyomavirus known as the causative agent of the fatal demyelinating disease, Progressive Multifocal Leukoencephalopathy (PML). Further, in experimental animals this virus causes a broad range of tumors of central nervous system origin. Recent studies have suggested the association of JCV with several human tumors most notably malignant brain tumors of childhood, medulloblastoma. The development of tumors by JCV is most likely through mechanisms involving inactivation of tumor suppressors and de-regulation of signaling pathways such as Wnt by the viral early protein, T-antigen. The neurotropic nature of JCV along with the overwhelming evidence for its oncogenic potential in laboratory animals and its detection in significant numbers of human medulloblastomas invite the re-evaluation of the role for JCV in the development of human brain tumors.

Animals↗

PubMed1997

[Mechanism of neuronal damage in AIDS].

Neurologic problems in AIDS are usually caused by opportunistic infections or secondary malignancy of the central nervous system (CNS), but brain damage occurs primarily as the result of HIV infection in CNS. In one of the typical opportunistic virus infections of CNS, progressive multifocal leukoencephalopathy (PML), oligodendroglial cells which maintain and support myelin sheaths are specifically attacked by JC virus. As the consequence, demyelination occurred, which could well explain the neuronal deficits. In contrast, in HIV the viral target cells are not neuronal cells, but infiltrating macrophages in CNS. Thus, the indirect injury such as HIV-related neurotoxic substances and macrophage-released cytokines would be augmented to induce diffuse neuronal damage in HIV infected brains. Recent discovery of co-receptor, chemokine receptor (CCR5) which is expressed in macrophages, may give a clue to understand the mechanism of HIV encephalopathy more precisely.

AIDS Dementia Complex↗

PubMed2004

HIV-1/AIDS neuropathology in a Canadian teaching centre.

BACKGROUND: The nervous system is a major target of HIV-1 infection and site of many complications of AIDS. Most of our knowledge pertaining to the range and frequency of neuropathology in HIV-1/AIDS is from large centres outside Canada in different social and health care settings. The goal of the present study was to describe HIV-1/AIDS-associated neuropathology before and during the era of highly active antiretroviral therapy at a Canadian teaching centre. METHODS: The records of the Department of Pathology, London Health Sciences Centre were electronically searched for cases of HIV-1/AIDS that came to postmortem examination since 1985. The clinical records and pathological materials were reviewed. RESULTS: Sixteen autopsies of HIV-1/AIDS were identified. All patients were male. Fourteen contracted HIV-1 through high risk homosexual activity, one through the transfusion of blood products and one through intravenous drug use. Three patients (19%) had pre-mortem evidence of HIV-1 associated dementia. At autopsy, 12 of the 16 cases had neuropathological findings and the most common diagnoses were HIV-1 encephalitis, progressive multifocal leukoencephalopathy, toxoplasmosis, and primary CNS lymphoma. CONCLUSIONS: High risk homosexual activity was a more prominent factor in acquiring AIDS in cases coming to postmortem examination compared with previous reports from most larger urban centres outside Canada where injection drug use and high risk heterosexual activity factored prominently. The incidence of HIV-1 associated dementia was similar to that reported previously. This study confirms the heavy burden and wide spectrum of disease experienced by the nervous system in HIV-1/AIDS.

AIDS Dementia Complex↗

PubMed2003

An overview: Human polyomavirus JC virus and its associated disorders.

JC virus (JCV) is a polyomavirus infecting greater than 80% of the human population early in life. Replication of this virus in oligodendrocytes and astrocytes results in the fatal demyelinating disease progressive multifocal leukoencephalopathy (PML) in immunocompromised individuals, most notably acquired immunodeficiency syndrome (AIDS) patients. Moreover, recent studies have pointed to the association of JCV with a variety of brain tumors, including medulloblastoma. The JCV genome encodes for viral early protein, including large and small T antigens and the newly discovered isoform T', at the early phase of infection and the structural proteins VP1, VP2, and VP3 at the late stage of the lytic cycle. In addition, the late gene is responsible for the production of a small nonstructural protein, agnoprotein, whose function is not fully understood. Here, we have summarized some aspects of the JCV genome structure and function, and its associated diseases, including PML and brain tumors.

Humans↗

PubMed1980

[Progressive encephalopathy in 3 cases of chronic lymphoid leukemia].

Three patients suffering from a lymphoproliferative syndrome developed, late in the course of the disease, a neurological disorder with the signs and symptoms of a progressive multifocal leukoencephalopathy (PML). This diagnosis was confirmed in the first patient. In the second, neuropathological examination revealed spongy and fibrous scars which could be evidence of an earlier lymphomatous infiltration. The diagnosis of the third patient was uncertain since no autopsy was made in this case. The involvement of the CNS in the evolution of lymphoproliferative disorders becomes more and more frequent, probably due to the prolonged survival time of patients undergoing chemotherapy and the immunosuppressive effects of such treatment. Biopsy is the only method of distinguishing PML from a cerebral leukemic infiltration; this is obviously important in view of the different therapeutic approaches used for the two diseases.

Aged↗

PubMed1993

Cellular changes in the cerebellar granular layer in AIDS-associated PML.

Six cases of AIDS-associated progressive multifocal leukoencephalopathy (PML) exhibited peculiar cellular changes in the cerebellar granular layer. These cells without discernible cytoplasm showed hypochromatic nuclei about twice as large as those of normal granule cells. They were restricted exclusively to the granular layer and always surrounded PML foci. An astrocytic, leukocytic or macrophage/microglial nature was largely excluded by immunocytochemistry. Human immunodeficiency virus (HIV) antigen p 24 could not be found in these cells and there was no unequivocal detection of JC virus (JCV) DNA and no ultrastructural evidence of papovavirus particles in them. They possibly represent altered cerebellar granule cells abortively or latently infected with JCV.

Acquired Immunodeficiency Syndrome↗

PubMed1990

Use of CT and MR imaging to distinguish intracranial lesions and to define the need for biopsy in AIDS patients.

To explore the potential usefulness of imaging studies in the diagnosis of focal central nervous system (CNS) lesions associated with acquired immunodeficiency syndrome (AIDS), the authors retrospectively examined the radiographic studies of 149 AIDS patients who presented with signs and symptoms of the three most common focal CNS lesions. Of these patients, 74 (50%) had Toxoplasma abscesses, 45 (30%) had primary CNS lymphoma, and 30 patients (20%) had progressive multifocal leukoencephalopathy (PML). Magnetic resonance (MR) imaging was more sensitive than computerized tomography (CT) in detecting lesions, especially in cases of PML. Whereas CT was unable to distinguish mass lesions caused by toxoplasmosis from those caused by lymphoma, 71% of the solitary lesions seen on MR images were lymphomas. These results indicate that empirical treatment for toxoplasmosis, the most common initial treatment for AIDS patients with neurological symptoms stemming from mass lesions, is not likely to be successful for patients with solitary lesions on MR images. Rather, early biopsy is advisable. If the presence of lymphoma is confirmed, the rapid initiation of treatment can allow prolonged high-quality survival.

Acquired Immunodeficiency Syndrome↗

PubMed1983

Neurological complications of acquired immune deficiency syndrome: analysis of 50 patients.

Fifty patients with acquired immune deficiency syndrome had complications affecting the central or peripheral nervous systems or both. The patients were either male homosexuals, intravenous drug abusers, or recently arrived Haitian refugees. They ranged in age from 25 to 56. Central nervous system complications were of four kinds: (1) Infections included Toxoplasma gondii abscesses in 5 patients, progressive multifocal leukoencephalopathy in 2, cryptococcal meningitis in 2, Candida albicans in 1, and possible Mycobacterium avium intracellulare in 3. Eighteen patients suffered a subacute encephalitis possibly attributable to cytomegalovirus infection. (2) Tumors consisted of primary lymphoma of the brain in 3 patients and meningeal invasion by systemic lymphoma in 4. (3) Vascular complications included nonbacterial thrombotic endocarditis in 2 patients and cerebral hemorrhages in the setting of thrombocytopenia in 3. (4) Undiagnosed central nervous system problems were evidenced as focal brain lesions in 3 patients and self-limiting aseptic meningitis in 4. Peripheral neuropathy occurred in 8 patients.

Acquired Immunodeficiency Syndrome↗

PubMed2000

Stereotactic biopsy of cerebral lesions in AIDS.

Stereotactic brain biopsy was used to establish diagnoses of conditions in patients with AIDS. Two hundred fifty stereotactic biopsies and one open resection were performed for 243 patients. Pathologically abnormal tissue was obtained in 246 (98%) of the procedures, and 16 patients (6%) had >1 diagnosis. Diagnoses included lymphoma in 82 (33%), progressive multifocal leukoencephalopathy in 73 (30%), and tumors not ordinarily associated with AIDS in 7 (3%). In one-third of the cases, the tissue diagnosis differed from the predicted diagnosis. Four of the first 32 patients (12%) developed intracranial bleeding hours after surgery, which was fatal in 3 (9%). Subsequently, all patients were treated with a coagulopathy protocol that included preoperative and postoperative administration of coagulation factors, and there were no further instances of delayed bleeding in the 218 subsequent patients. Among those later patients, there were 7 complications (3%), leading to 4 deaths (2%), a complication rate that compares favorably with that among patients without AIDS.

AIDS Dementia Complex↗

PubMedDate not supplied

[Infectious and metabolic nervous system complications of systemic cancer].

OBJECTIVE: To review the incidence and causes of the infections and metabolic diseases of the nervous system in patients with systemic neoplasias. DEVELOPMENT: Patients with immunodeficiency, particularly those with hematological neoplasias and persons treated with immunosuppressive drugs have a considerable tendency to infection due to opportunist germs. Infections of the nervous system are relatively rare (0.02%-1%) and the commonest neoplasms are lymphomas, especially those of Hodgkin type and lymphosarcomas. The most frequent infections are caused by the herpes virus, meningitis due to Listeria monocytogenes and the meningitis due to fungi (Aspergillus, Candida and Cryptococcus). Cerebral abscesses, although rarer, are relatively common and are caused by gram negative bacteria, fungi and toxoplasmosis. In recent years there has been a notable increase in the number of patients diagnosed as having progressive multifocal leukoencephalopathy due to the possibility of carrying out studies to detect the DNA of the JC virus by polymerase chain reaction techniques. Empirical treatment of patients with neurological infections and systemic cancer should be started following the guidelines for immunodepressed patients. The metabolic complications of these patients are mainly due to hormone overproduction, hydroelectrolytic changes and vitamin deficits, which in general cause alterations of mental function of the confusion state type. CONCLUSION: In all patients with an infection or metabolic complication involving the nervous system, the presence of a systemic neoplasm makes it necessary to vary both the diagnostic approach and the empirical therapeutic measures taken.

Acute Disease↗

PubMed1997

[Slow virus infection].

Subacute sclerosing panencephalitis (SSPE) and progressive multifocal leukoencephalopathy (PML) are the major slow virus infections of humans. SSPE is caused by mutant measles virus after long persistence in the brain. Its pathogenesis is discussed, based on accumulating data on molecular properties on measles virus prevalent in the field as well as recent identification of measles virus receptor. Current situation on the therapy of SSPE is also described. PML is caused by the infection of oligodendroglia with persisting JC virus. Its pathogenesis is discussed based on the molecular properties of the archetype and PML type of JC virus, and on the recent findings on the involvement of JC virus T antigen in demyelination. Increase in the incidence of PML in patients with AIDS is discussed in view of the interactions between HIV and JC virus.

Humans↗